Heat exchangers that utilize water for transferring heat are well known. Two examples of these heat exchangers are boilers and cooling towers. As steam is produced by the boiler or as water evaporates from the cooling tower, mineral deposits are typically left behind. Ordinarily, more minerals are introduced by way of the water added to make up for the water lost to steam or evaporation. Eventually, the accumulation of mineral deposits on heat transfer surfaces may reach a level that substantially impedes heat transfer. In addition, the higher concentration of minerals may also result in corrosion of the heat exchanger thereby further decreasing the efficiency of the heat exchanger.
One proposed solution for the accumulation of mineral deposits, e.g. scale build-up, is a process known as blowdown. Blowdown is the process of discharging water saturated with mineral deposits from the heat exchanger. Although this process may successfully decrease the level of mineral deposits within the heat exchanger, it also typically introduces a variety of new problems. One skilled in the art will understand that these problems usually include wasted energy, water, and chemicals used to treat the water. In particular, energy typically is wasted because the discharged blowdown water has the same temperature as that of the steam generated in the boiler. Additionally, water and chemicals are clearly wasted because the discharged blowdown water ordinarily is no longer reused by the heat exchanger.
Another proposed solution utilizes a reverse osmosis system (RO system) for filtering out the undesired mineral deposits from the water and decreasing the volume of heated water and chemicals discharged from the heat exchanger. Ordinarily, the RO system is in operative connection between the heat exchanger and an evaporation pond. As substantial amounts of mineral deposits accumulate within the heat exchanger, the water typically is passed from the heat exchanger to the RO system. The RO system usually removes the mineral deposits and returns a portion of the water to the heat exchanger thereby recycling the heated water. The RO system also typically rejects the mineral deposits with some of the water to an evaporation pond or various other kinds of waste vessels.
A drawback of this proposed solution is that a relatively excessive amount of water still is ultimately discharged from the heat exchanger. In particular, this proposed solution typically recycles only about 75% of the water for reuse by the heat exchanger. The remaining water that is discharged to the evaporation pond still represents a significant portion of water, heat, and chemicals that are wasted, albeit to a lesser degree as compared to the previous proposed solution mentioned above.
Therefore, a need exists for a method and system of heat transfer that recycles a greater portion of the heated water and chemicals for reuse by the heat exchanger.